This invention concerns a process for the preparation of ether-containing chlorides of the general formula EQU R.sup.2 (OR.sup.3).sub.n Cl III
which are known to be useful as solvents as well as in the preparation of polymers, pharmaceuticals, etc.
Various methods have been employed for the preparation of ether-containing chlorides. Some of these methods include the chloroethylation of dioxane disclosed in U.S. Pat. No. 2,383,091 and of polyoxyethylene diols disclosed in U.S. Pat. No. 2,352,745. Also, Teramura and Oda, Chemical Society of Japan, 54, 605 (1951), disclose the preparation of 1,2-bis(2-chloroethoxy)ethane by the copper catalyzed coupling of 2-chloroethyl-1-chloromethyl ether. G. F. Zellhoefer, in Industrial Engineering Chemistry 29, 548 (1937), discloses the preparation of this same dichloro-substituted ether from triethylene glycol and thionyl chloride. No details of the reaction or yields, however, are disclosed. U.S. Pat. No. 3,294,847 discloses the preparation of the desired ether-containing chlorides by the action of phosphorous trichloride on certain ether-alcohols, ether-glycols and polyglycols in the presence of hydrogen chloride.
Many of the existing methods for preparing ether-containing chlorides are not completely satisfactory due to low yields of the desired product obtained or because of undesired mixtures of by-products which accompany the formation of the product compound and which are difficult to separate by conventional methods.
It is known that ether linkages, in the presence of good nucleophiles such as alcohols, are particularly susceptible to cleavage by strong acids such as hydrogen chloride. It, therefore, is apparent that any process modifications which reduce this potential would be highly advantageous since higher yields and increased product purities can be expected where the potential for ether cleavage is reduced or eliminated.
An improved process has now been found whereby ether-containing chlorides can be obtained in high yield, up to about 94% of theory, in short reaction times, without high levels of undesired mixtures of by-products, and without high reaction temperatures. By the process of this invention hydroxy-containing compounds such as ether-alcohols, ether-glycols and ether-polyglycols are reacted with certain chlorinating agents in the presence of a catalytic amount of certain quaternary ammonium salts.